U.S. Park Police responded Thursday to a report of vandalism on the west lawn of the Washington Monument, where the numerals “8647” were marked in the grass, according to a statement from the agency.

Live webcam footage from atop the Washington Monument as of Thursday afternoon showed the markings, with a highly visible “8” along with less visible “6,” “4” and “7,” the Guardian reported.

“At approximately 11.30am, US Park police responded to a report of vandalism of the west lawn of the Washington Monument,” the U.S. Park Police said in a statement. “The numbers ‘8647’ were marked in the grass.”

The agency said the cause of the discoloration has not yet been determined and that grass samples have been collected for testing. The investigation is ongoing.

A U.S. Department of the Interior spokesperson called the incident “deranged vandalism,” saying: “Any threat against the president is taken very seriously by the department, and our US Park police will investigate this incident and hold those responsible accountable.”

The numerals “86” are widely used across the restaurant industry to mean “stop” or “get rid of” something, while Donald Trump is the 47th president of the United States.

It remains unclear when or how the numbers were etched into the ground.

The incident comes just weeks before the United States marks its 250th anniversary, with a series of events planned across the National Mall as part of the “Great American State Fair,” as MSI previously reported. It also follows extensive renovations to the area overseen by the Trump administration, including a $13.1 million makeover of the Lincoln Memorial Reflecting Pool that transformed it from a “gray stone” appearance to an “American-flag blue.”

The etching is the latest in a series of incidents involving the numerals “8647” and the president. In April, former FBI Director James Comey was charged with two felonies, including making a threat against the president and transmitting that threat across state lines via social media, over a picture he posted on Instagram that depicted seashells